'Arseniclife' bug lacks arsenic in genome's DNA

Visions of aliens danced in a lot of heads last December, when NASA held a press conference, promising an "astrobiology finding that will impact the search for evidence of extraterrestrial life."

What scientists disclosed was the discovery of a bacteria, pulled from California's Mono Lake, that added deadly arsenic to the list of six basic elements believed needed for life — carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus. The idea that a microbe could bring poisonous arsenic into its DNA and thrive threw the conventions of biology on its head.